1. Field of the Invention
The present invention relates to a hybrid hot air heater incorporating a gas heater and an electric heater into one chassis.
2. Description of the Related Art
A conventional hybrid hot air heater is disclosed in, for example, Jpn. Pat. Appln. KOKAI Publication No. 2000-9347. This conventional hybrid hot-air heater incorporates a combustion heater unit provided with a combustor that uses petroleum etc. as a fuel and an electric heater unit provided with an electric heater, into a chassis having an outlet on its front face and an inlet in its rear face. For this case, air-blowing systems for taking in combustion air from the room into the chassis and blowing out hot air heated at the respective heater units are controlled by one air-blowing fan provided at the rear of the chassis.
However, if the air blowing system for the combustion heater unit and that for the electric heater unit are controlled by one air-blowing fan, the generated heat quantity will be different between a case in which the electric heater is operated together with the combustion heater and a case in which the combustion heater is operated alone with the electric heater turned OFF. This means different quantities of intake air must be blown into the chassis in these different cases to prevent overheating. Different quantities of air are combusted in these different cases, thus making it difficult to operate the combustion heater with stability.
In view of the above, it is an object of the present invention to provide a hybrid hot air heater that can always operate a combustor of a combustion heater unit with stability irrespective of whether an electric heater unit is operating or not.